Buy a quart first instead of a large quantity in case you’re not committed to the color. Paint a piece of foam board and move it around the room to see how the light affects the color at different times of the day.
A good old fashioned, quality paint brush.
Get a good quality paint brush and take good care of it. It's a lot less time intensive to use a good brush and make a good line than it is to have to tape it first.